Internal-combustion engine



INTERNAL COMBUSTI ON ENGINE Filed Jan- 11, 1927 [N V EN TOR.

W 7 5 W A TTORNEYS.

Patented J1me 7, 1927.

UNITED STATES 1,631,706 PATENT, OFFICE.

EDWARD soxAL, or new YORK, n. Y., ASSIGNOR 'ro; AMEItICAN KATALITE con- ZPORA'LION, or nnooxnxn, NEW YORK, A CORPORATION or DELAWARE.

INTERNAL-COMBUSTION ENGINE.

Application filed January 11, 1927. Serial No. 160,327.

This invention relates to internal combustion engines, to correlated nnprovements and discoveries whereby and wherewith the op- -'eration thereof is enhanced, and more particularly to the prevention of detonation in the combustion chamber thereof.

An object of "the invention is directed to the-provision in an internal combustion engine of an improved detonation counterac tant.

Another object is to provide an improved method of permanently preventing detonatio n'in an internal combustion engine.-

A further object is to provide an improved coating composition which may be affixed to the walls of the combustion chamber of an internal combustion engine to prevent detonation therein.

This application is a continuation in part of my copending application SerialNo. 142,- 247, filed October 18, 1926.

In my copending application, Ser. No. 42,583, filed July 9, 1925, I haveshown-that the tendency toward detonation in an internal combustion engine, particularly the pro nounced tendency thereto in high compression engines, may be counteracted by fixedly disposing within the combustion chamber of the engine a material capable of undergoing a reversible endothermic, i. e., heat-absorbing, changewithin the range of temperatures and amid the other conditions existent in the engineduring operation, by means of which a cooling efiect is exerted upon the gaseous mixture within the chamber with a resultant counteraction of detonation.

While it is well recognized thatv detonation of the gaseous mixture within a combustion chamber can be counteracted by cooling the mixture, no theory offered in explanation of this phenomenon has been universally accepted. It is my view that detonation, or knocking, in internal combustion engines,

' is mainly due to a decomposition -or breaking down of the unburned fuel, or in other words, to the dissociation of the'larger molecules of the fuel under the'influence of heat and pressure into a greater number of smaller molecules, whereby there is caused a sudden rise of pressure. 'This rise of pressure may not be indicative of the true pressure condition within the whole body of the fuel-air mixture, but is rather in the nature of a localized'impact. This view is supported by the following considerations:

First, the detonating tendency of various fuels is practically a function of their thermal stability, for example, the tendency to detonate decreases in the following order: kerosene, ordinary gasoline, aromatic gasoline, benzol, alcohol and hydrogen, and the thermal stability increases in the same order. Second, the indicator diagram of detonating engines shows a very rapid rise of pressure which lasts only a very short period of time, is followed by an equally rapid decline, frequently occurs several times at the beginning of the expansion stroke, the peaks becoming smallereach time, and these rises of pressure are of such short duration that the corresponding pressure volume area is too small to represent an appreciable amount of useful work and hence they manifest themselves as destructive impacts. Third, detonation is accompanied by lost power, deposition of carbon and great loss of heat to the water jacket, which loss of power and deposition of carbon may be considered natural results from the decomposition of the fuel, and the loss of heat to the water jacket is probably due to radiation caused by glowing particles of carbon and to the impacts. Fourth, it has been shown that various factors which cause an increase in the rapidity of combustion and make the combustion more complete have a rather pronounced effect in counteracting detonation. This would seem to follow as an indirect result of the fact that the molecules of the fuel cannot simultaneously undergo a reaction of combustion and of decomposition.

In my copending application above referred to, I have disclosed as an exemplifies.- tion of a detonation counteractant suitable for use in accordance with the invention, a material, the melting point of which is. such as to render it capable of undergoing a reversible change from solid to liquid state under the conditions of engine operation, and I have particularly suggested the use of lead, antimony and tellurium. I

I have now found as a result of continued experimentation that an especially effective which it is employedso as to be converted into a 'diflerent non-fugitive, preferably solid, chemical material, which latter. material is capable under the conditions of engine operation of undergoing, at the lower the definition of vmy improved detonation counteractant given above, or a substance which is convertible into such material under the conditions of engine operation. It will be appreciated in this connection that since the invention relates to internal combustion engines, the term chemically endothermically reactive material as employed hereinafter includes only such substances as will undergo the desired reactions within the range of temperatures and under the other conditions found within the combustion chamber of the engine in which it is employed.

A chemically endothermically reactive material is particularly advantageous for use as a detonation counteractant within the combustion chamber of an internal combustion engine because of the marked heat absorption during the endothermic reaction, with the consequent high cooling effect upon the gaseous mixture. Furthermore, when there is employed a solid material which vis converted into another solid. material under the conditions contemplated by the invention, a further advantage is to be found in the elimination of any possibility of the loss of the detonation counteractant by the escape of a material which has been converted into a fluid state.

In the practice of the invention a material capable of undergoing reversible chemical change which is endothermic during the power stroke, when the temperatures within the chamber are the highest and the consequent tendency toward detonation is the greatest, is fixedly disposed within the combustion chamber of. an internal combustion engine,preferably in the form of, or as an ingredient of, a coating applied to certain portions of the walls of said chamber. This coating is especially effective when applied to certain of those portions of the chamber walls which are hottest during operation, as,

for example, the exposed surface of the piston and/or the exposed surface of the exhaust valves. s

The accompanying drawing is a partly sectional view exemplifying a form of the invention. In this exemplification a cylinder vblock 1, together with a high compression'cylindcr head 2, provides a combustion chamber 3 into which the contacts 4:.0f a spark plug 5 extend. A portion of the wall of the combustion chamber is provided by a. piston head 6 on the surface of which is a coating 7 containing a relatively permanent chemically endothermically reactive material. Another portion of the wall of this chamber is provided by the surface ofan exhaust valve 8 on which there may also be provided a coating 9 which may also contain a relatively permanent chemically endothermically react1ve material.

As an exemplification of suitable materials for use in accordance with the present invention, mention is made of the carbonates (acid and normal) and the oxides of the alkaline earth metals, calcium and magnesium, 1 and of the alkali metals, sodium and potasslum. The exact reactions which such compounds undergo within the engine is difficult of determination and will probably vary to a certain extent with the particular. operating conditions of different engines. However, it appears probable that the bicarbonates of certain of these metals may undergo a reversible change, which in the. case of 'calcium may be represented chemically by the equation and that the normal carbonates of certain of the metals may undergo a reversible heat-absorbing change which in the case of calcium may be represented chemically by the equation the symbols +A and- A indicating absorption and release of heat, respectively. tither of these equations may represent the effective endothermic reaction occurring when one of the carbonates of calciumor calcium oxide is initially applied to the walls of the combustion chamber of an engine, but it is more likely that both reactions occur, giving a cumulative effect. In any case, whichever of the'three calcium compounds mentioned is originally applied to the walls of the chamber, the proper effective material will soon be formed, so that during the power period of engine operation, when the range of temperatures within the chamber is the greatest, this efl'ective compound. will undergo a change into .a' compound which is reconvertible into the effective compound during those intermediate periods of operation when the range of temperatures within the chambers is lower, In view of the above, 130

' it is to be understood that the term comber walls, or in lieu thereof the bicarbonate,

Ca(HCO or the oxide, OaO. may be employed. There may also be used a mixture of two or more of these materials. cases of certain other alkali and alkaline earth compounds it may be more desirable to use one or] another of the types of compounds mentioned.- It is of course to be appreciated that other types of compounds of metals included in the alkali and alkaline earth groups are not excluded from the purview of this specification.

In order properly to secure it to the chamber walls, the improved detonation counteraciant, in finely divided form, may be admixed with a suitable binder, such as a silicate. For example, an intimate mixture of a finely divided chemically endothermically reactive material with a silicate binder may be applied in the form of a coating onthe exposed surface of the piston head, and/or such other portions of the walls as may be desired. The proportions of active substance to the binder may be'varied to the req irements of the particular case, and it has been found that satisfactory results are produced when a mixture containing 50% ofa calcium compound of the carbonate-oxide type and 50% of a silicate is employed, though these proportions may be varied widely. The application may be accomplished .by cleaning the desired surface area, coating such area with the detonation counteractant, and baking or setting. This procedure may be repeated, if desired, until several coats have been applied. The amount of the improved detonation.counteractant to be applied in a particular type of engine may be readily determined by suitable tests indicating the proper surface area to be coated in order to obtain eflicient operation.

At the present time the phenomenon of detonation, or knocking, during the operation of internal combustion engines is of much interest because, other conditions being equal, it is more pronounced with en-- gines of high compression ratios. Accordmgly, this tendency to detonate with a given fuel becomes practically a limiting factor for improvement in the thermal efliciency' and power output through an increase in the compression ratio. This is particularly the case with the constantvolume cycle type In the of engine which is used almost exclusively in automobiles and in aeroplanes and also to a considerable extent insmall marine and stationary engines.

It is true that there are other limiting factors, such as loss in mechanical efliciency, which may offset the gain in thermal eflieiency after a certain increase in the compression ratio, but the limitation due to the injurious effects of detonation becomes operative before these other limiting factors exert their influence. Accordingly, it will be apparent that the'present invention, because of'the marked effectiveness of a chemically endothermic-ally reactive material as a detonation counteractant, will permit the designing of engines having a higher compression ratio than has heretofore been possible.

Among the other advantages arising through the utilization of the detonation counteractant, mention may be made of the following: lack of detonation or knocking, lower fuel consumption, more flexible operation of the engine, decrease in carbon deposition, and an increase in the thermal efficiency, particularly in connection with the use of high compression engines.v

It is, of course, to be understood that the invention .does not contemplate the use of a material of such a'nature that a compound appearing onjeither side of the equation expressing the reaction occurring within the chamber has a known cracking effect or other property 'which would tend to overbalarice the 'eflective anti-detonating efiect- I'produce'd byheat absorption during the endother'mic reaction.

While the theory" herein presented offers a basis for an understanding of the manner in which the detonation counteractant may function; and while it is sup orted by known facts, it is to .be understoo of course, that the operativeness and. racticability of the invention is not depen ent upon or limited in any way by the correctness of such theory.

Since certain changes may be made in the detonation gcounteractant above described, and difierent embodiments. of the invention could be made without departing from the .scope thereof, 'it is intended that all matter contained in the above description shall be interpreted as illustrative and'not in a limiting sense. 1

It is also ing claims are intended to cover all ofthe generic and specific features ofthe invention herein described, and all statements of ios to be understood that the follow- F the scope of the invention -which,;as a matter of language, might besaid to fall there'- between. v

Having describedmy invention, what I claim as new and desireto secure ters Patent, is:

1. In an internal combustionengine, the

combination with a combustion bbamber, of

y t i ,a chemically endothermically reactiye compound of a metal included in the alkali and combination with a combustion chamber, of

a chemically endothermically reactive compound of a metal included in thealkaline earth group fixedly disposed within said chamber.

4. In an internal combustion engine, the combination with a combustion chamber, of a chemically endothermically reactive compound of a metal included in the calciummagnesium sub-group of the alkaline earth metals fixedly disposed within said chamber,

said compound being a compound of the carbonate-oxide type.

5. In an internal combustion engine, the combination with a combustion chamber, of

a coating formed on certain of the walls of said chamber, sa1d coating contamlng a calcium compound of the carbonate-oxide 30 type.

6. In an internal combustion engine, the

combination with a. combustion chamber, of a coating formed on certain of the walls of said chamber, said coating containing a carbonate of calcium.

7. In an internal combustion engine, the combination with a combustion chamber, of a coating fixedly disposed on certain of the walls of said chamber, said coating including a binder'and a chemically endothermi-- cally reactive compound of a metal included in the alkali and alkaline earth groups.

8. In an internal combustion engine, the combination with a combustion chamber, of a coating fixedly disposed on certain of the walls of said chamber, said coating inclu-ding a binder and a compound of a metal of the calcium-magnesium sub-group of the alkaline earths, said compound being a com- 5 pound of the carbonate-oxide type.

In testimony whereof I affix my signature.

EDWARD SOKAL. 

